The invention relates to a photoelectric smoke detector, more specifically the invention relates to a photoelectric smoke detector for detecting smoke particles comprising a light emitting element, a light receiving element for receiving light emitted by the light emitting element and scattered by the smoke particles and for outputting a detection signal obtained by photo-electrically converting the received light, and an amplifier circuit for amplifying the detection signal and providing an amplified output signal, wherein the amplified output signal may be divided into an offset-signal and an amplified detection signal, whereby the photoelectric smoke detector is adapted to operate in a pulsed mode, so that the detection signal comprises high-frequency components. The invention furthermore relates to a process for testing the photoelectric smoke detector.
Photoelectric smoke detectors are widely used in private households as well as in industrial or public environments as detecting devices, which allow an early detection of smoke particles and therefore an early detection of fire.
A photoelectric smoke detector and a disaster monitoring system using a photoelectric smoke detector is disclosed in the European Patent Application EP 755 037 A1, probably representing the closest prior art. The smoke detector comprises a light emitting element for emitting light, a light receiving element for receiving the light emitted from said light emitting element and outputting a detection signal obtained by photo-electrically converting the received light and a calculation/comparison unit for calculating the level difference or the level ratio between the light emission zero point detection signal from said light receiving element which has received the light from said light emitting element and the putting-off zero point detection signal from said light receiving element when said light emitting element is put off and comparing the level difference or the level ratio with a preset determination level and a determination unit for determining the normality or the abnormality of the operation of said light emitting element, said light receiving element and a peripheral circuit from the result of comparison effected by said calculation/comparison unit.